Apparatus for multiple heat treating



Feb. 3,' 1942. F. s. DENNEE N ETAL APPARATUS FOR MULTIPLE HEAT TREATING Filed Aug. 2, 1940 Patented Feb. 3, 1942 APPARATUS FOR MULTIPLE HEAT TRE ATIN

Francis S. Denneen, Cleveland, and WilliamC. Dunn, Shaker Heights, Ohio, assign'ors to The Ohio Crankshaft Company, Cleveland, Ohio, a

corporation of Ohio Application August 2, 1940, Serial No. 349,410

8'Claims. (Cl. 219-13) The present invention, relating as indicated to apparatus for the heat treatment of multiple parts, is directed chiefly to apparatus for surface harde'ning corresponding surface zones of a number of parts when production in large quantities is required. v 1

Heretofore, when it was required to harden a surface zone of an article, that surface zone was brought into a high frequency magnetic field where it was heated by current induced therein and was then quenched, the heating of the one zone usually having been completed before the heating of a second zone began. In our copending application Serial No. 253,168 filed January 27, 1939, we have disclosed means for simultaneously hardening two cams one on each two camshafts, the means therein disclosed being related in some respects to the apparatus shown and described hereinafter. In this former application, the general form and construction of an inductor for hardening two articles simultaneously by current from one transformer was shown, but the proportions of the inductor and of the unequal openings in the inductor for obtaining simultaneous and equal heating were not fully described.

When it is required to harden large volumes of parts which may or may not be alike, considerable power and equipment are saved by using one transformer with one source of power instead of several smaller transformers. Further, the inductors carrying the heating current are much less numerous and require less space than several small independent conductors. It is thus not only possible to save power and increase efl'iciency, but to save space and cost of machinery. With these conditions in view the object of the present invention is-to provide simple and inexpensive equipment for heat treating metallic parts. A further object isto provide simple means for heat treating such parts in large volume. Another object is to provide means in which such hardening can be accomplished with high efiiciency and with a minimum. loss of power and without appreciable variation in th results obtained. a With these and other objects in view said invention then consists of the means hereinafter described in connection with the annexed drawing together with the method employed. It will be understood that the scope of this invention is not to be regarded as being limited to the form hereinafter described, but that it 'may from this disclosure, but within the scope of the appended claims. I

In said annexed drawing Figure l is an eleva tion of one form of our multiple inductor. Figure 2 is a plan view of the inductor shown in Figure 1. Figure 3 is a plan view of another form of our multiple inductor; and Figure 4 is an elevation of the inductor shown in Figure 3.

In general this invention comprises any. arrangement of conductors in which current from one source such as from the secondary of a transformer is caused to flow simultaneously around parts of several articles or around several parts of the same article to induce heating currents in the surface zones of these parts so as to bring these zones to a prescribed temperature. It also comprises so forming these conductors and their supply connections as to cause all the surface zones to reach the prescribed temperature at substantially the same time or, when required, to cause one of the surface zones to reach a prescribed temperature at a definite time interval before another zone reaches. that temperature.

This makes it possible to heat treat rapidly and in large quantities parts which may be alike or which may be different.

Referring now particularly to Figures 1 and 2 of the drawing, current of suitable frequency and voltage is supplied from generator ll to the primary i2 of the focus inductor transformer whose secondary I3 is connected directly to the inductor elements M, l5 and I6 by common bus bars such as H. Connections such as l8 are provided for circulating cooling water thru the secondary coils l3. Each of the three inductors shown has three openings so that nine surface zones are heated simultaneously. When it is desired to quench these surface zones while these zones are in heating position, the inductors are made hollow and quenching fluid is supplied from pipes such as'l9 and orifices are provided for delivering this fluid directly onto the heated surfaces. I

When a large number of larger areas are required to be heated simultaneously sometimes it is not expedient to divide the total current sup-' ply between a number of parallel inductors as in Figures 1 and 2, but it is necessary to pass all the current available through the inductors in series. When this is required, the inductors are arranged as in Figures 3 and 4. Current of suitable character is supplied to the transformer primary 20. The single turn secondary which appear in many embodiments differing in detail 55,

often is made of several hollow conductors connected in parallel, is'cut as at gaps 2| and 22 providing a secondary of two halves 23 and 24, the branches of each of the two inductors straddling a gap so that the current flowing thru one half of the secondary must pass thru both branches of each inductor and thru the other half of the secondary to complete its circuit. Each of the inductors is provided with several openings each adapted to receive parts to be heated. These openings are not always of equal size and number and all the openings in any one inductor are seldom of the same size, especially when the parts to be heated are substantially equal. One inductor may have more openings and openings of different size than the other inductor in series with it.

By extensive experimentation it has been found that the openings in the inductors must differ in size to obtain equal heating in equal or identical parts. This diiference in size of openings depends upon the distance of the first opening from the transformer center line, upon the distance between openings and upon the character of current being supplied. For instance, in considering the openings A, B and C of an inductor such as in Figure 2 for heating equal parts opening A is made of a diameter four percent larger than opening B and opening C is six per cent larger than B. When there are only two openings, such as A and B, opening C being omitted, opening B is made five per cent larger than A. When there are four openings as in Figures 3 and 4 openings E and F are made substantially of equal diameter. D is made six per cent larger and G is seven per cent larger than E or F.

Many modifications of the apparatus shown and above described will find commercial applications such as an arrangement similar to that of Figures 3 and 4, but having two parallel inductors on one side and one or several on the other side of the transformer. Also, the use of inductors similar to those shown in Figures 3 and 4 have been provided for progressive heat treatment of several parts moving either continuously or intermittently along parallel lines.

Heating is accomplished in some cases by extending a single conductor along a group of articles which may be arranged in a straight line or in any other relative positions, and then rotating or oscillating the articles to distribute the heating current induced in the articles. The conductors are usually formed to lie closely to the zones of the articl which it is desired to heat.

Other modes of applying the principle of our invention may be employed instead of the one explained, change being made as regards the means herein disclosed, provided those stated by any of the following claims or their equivalents be employed.

We, therefore, particularly point out and dis tinctly claim as our invention:

1. In apparatus for inductive heating, a transformer having a primary and a secondary, cuts dividing the secondary into segments, an inductor member at each cut, said inductor member joining the segments at said out to provide a continuous series heating circuit thru the segments and the inductors, and means for supplying periodically varying current to the primary of the transformer.

2. In apparatus for inductive heating, a transformer having a primary and a secondary, the secondary havin cuts dividing the said secondary into segments, each of the segments having two terminals, heating inductors, each inductor being adapted to connect a terminal of one segment to a terminal of another segment at each cut, and

means for supplying periodically varying current to the primary to cause inducing current to flow in series in the segments of the secondary and in the inductors.

3. In apparatus of the class described, an in-- ductor comprising a longitudinally extending block of metal having an inner supporting end and an outer end, a group of substantially parallel passages extending thru the block, one of the passages being adjacent to the outer end of the block, a cut dividing the inner end of the block and extending longitudinally thru a part of the block to form two substantially parallel conductors, the

" cut passing substantially centrally of the passages varying current thru the conductors.

4. In apparatus of the class described, an inductor comprising longitudinally extending blocks, each block having an inner supporting end and an outer end, said blocks lying in substantially parallel relationship to form a group of blocks, a row of substantially parallel bores passing thru each block, one of the bores of each block lying adjacent to the outer end of the block, a

cut dividing the inner end of each block and extending longitudinally thru a part of the block to form two substantially parallel conductors, the cut passing substantially diametrally of the bores and cutting the walls of the bores on substantially opposite sides, the bore adjacent to the outer end of each block having its end adjacent side uncut to provide a conductor joining the parallel conductors at the outer end of the block, each bore in each block being in substantially co-axial relation with a corresponding bore in an adjacent block, and means having connection with the conductors at the inner end of the group of blocks for flowing inducing current thru the conductors.

5. In apparatus of the class described, an inductor comprising a longitudinally extending block of metal having an inner supporting end and an outer end, a group of substantially paral- V lel bores passing thru the block, one of the bores being adjacent to the outer end of the block, another of the bores being adjacent to the inner end of the block and a bore intermediate of the end adjacent bores, a cut dividing the inner end of the, block and extending longitudinally thru a part of the block to form two substantially parallel conductors, the cut passing thru the bores and cutting the walls of the bores on substantially opposite sides, the bore adjacent to the outer end of the block having its end adjacent side uncut to provide a conductor joining the parallel conductors at the outer end of the block, the bore adjacent to the outer end of the block and the bore adjacent to the inner end of the block being of substantially greater diameters than the intermediate bore, and means having connection with the inner end of the block for flowing inducing current thru the conductors.

6. In apparatus for simultaneously heating articles of substantially equal size, an inductor comprising a longitudinally extending block of metal having an inner supporting and and an outer end, two substantially parallel bores passing thru the block, one 01' the bores being adjacent to the outer end of the block and the other bore being adjacent to the inner end of the block, the bore adjacent to the outer end of the block being of greater diameter than the bore lying adjacent to the inner. end of the block, a cut dividing the inner end of the block and extending longitudinally thru a part of the block to. form two substantially parallel conductors, the out passing thru walls of the bores and cutting the wall of the inner bore on substantially opposite sides, the wall of the outer bore being cut on its side adjacent to the inner bore and being uncut on its side adjacent to the outer end of the block to provide a conductor joining the. parallel conductors at the outer end of the block, and means having connection with the inner end of the block for flowing periodically varying current thru the conductors.

'7. In apparatus for simultaneously heating a) multiplicity of articles of substantially equal size, an inductor comprising a longitudinally extending block of metal having an inner supporting end and an outer end, two substantially parallel bores passing thru. the block, one o! the bores being adjacent to the outer end of the block and L the other bore being adjacent to the inner end of the block, and otherbores lying intermediate of the said end adjacent bores, the intermediate bore lying adjacent to the outer end adjacent bore being of greater diameter than the intermediate bore lying adjacent to the inner end adjacent bore. a cut dividing the inner end of the block and extending longitudinally thru a part of th block to form two substantially parallel conductors, the cut passing thru the walls of the bores and cutting the walls of the bores on substantially opposite sides, the 'wall of the outer bore being cut on its side adjacent to an inter-1 mediate bore and being uncut on its side adjacent to'the outer end of the block to provide a conductor joining the parallel conductors at the outer end of the block, and means for supplying periodically varying current to the parallel conductors.

8. In apparatus of the class described, a transformer comprising a primary coil and a secondary coil, the said secondary coil having openings, the openings being spaced along the coil, inductors being connected to said secondary to .2 bridge the said openings, each of said inductors comprising two conductors, said conductors being spaced at selected points to receive articles to be heated, and means for supplying periodically varying current to the primary to induce current in said secondary and to cause said current to flow thru said secondary and thru said inductors in series.

FRANCIS S. DENNEEN. WILLIAM C. DUNN. 

